Many air conditioned buildings are used only cyclically with periods of high cooling load alternating with periods of low cooling load. Offices, for example, are commonly on an approximate twelve-hour daytime-nighttime cycle of use and non-use and churches have even more and longer periods of nonuse alternating with the use during a given week. The average load is thus for lower than the peak load. Even so conventional air conditioning systems for such buldings typically are sized to meet a full cooling load though such overcapacity is plainly inefficient and expensive both in initial cost and in operation. It is the purpose of the present invention to provide a cyclic load air conditioning method of maximum efficiency. The components of the system, which are not novel as such, include a heat-operated absorption chiller preferably utilizing ammonia as a refrigerant absorbed in water, an electric generator driven by a fuel-fired engine, a conventional electric chiller, and valving which includes temperature modulating valves and automatic diverting valves. An ice bank is provided in the system of the invention such as are disclosed in my U.S. Pat. Nos. 4,294,078 and 4,403,645.
By applying the concept of ice storage to buildings which have alternating periods of high and low cooling loads, the size of the components of the system can be kept to a minimum because scaled-down equipment can operate over a protracted period to store cold gradually in the ice bank and then during high cooling load operation the stored cold can augment the cooling output of the air conditioning components. The efficiency and first cost savings of the method of the invention increases with the ratio of the nonuse to use of the building and it is desirable that the period of use be no greater than the period of non-use during a given cycle. An office or other business or public place occupied for twelve hours and unoccupied for the same period each day can therefore benefit by the air conditioning method of the invention. The efficiency and first cost savings are even greater when the occupied hours are less, so that in churches, for example, where perhaps only six or eight hours of cooling during a week are required the cost savings of the method of the invention are extraordinary.